Recent and ongoing innovations in fiber optic technology have resulted in the increased use of optical fibers in a number of applications, including optical communications. This increased use has lead to a need for efficient peripheral devices that assist in the transmission of data through the optical fibers. One such peripheral device is the optical switch. An optical switch operates to selectively couple one optical fiber to a second optical fiber such that the coupled optical fibers are in communication with each other.
Two optical fibers in an optical switch can be coupled together with micro-machined tilting mirrors, or microelectromechanical system (MEMS) tilting mirrors, to direct a beam of light from an input optical fiber to an output optical fiber. FIG. 1 illustrates a simplified diagrammatic side view of an optical switch according to the prior art. The optical switch 100 includes input optical fibers 102, output optical fibers 104, two arrays of tilting mirrors 106, 108, and a fixed mirror 110. During the transmission of information through optical switch 100, a beam of light 112 is transmitted from an input fiber 114, reflected off tilting mirror 116, reflected off the fixed mirror 110, and directed to an output optical fiber 118 by tilting mirror 120. Although only one beam of light 112 is illustrated in FIG. 1, there are in actuality a number of beams of light propagating through optical switch 100 at any given time.
The alignment of the tilting mirrors is critical to the performance of an optical switch. Each tilting mirror must be precisely aligned to receive a beam of light from, or transmit a beam of light into, a corresponding optical fiber. When one or more tilting mirrors are out of alignment, less light enters an output optical fiber resulting in losses in optical signal power. One factor that increases the difficulty of aligning the arrays of tilting mirrors 106, 108 is the small acceptance angle of the output fibers 104. The beam of light 112 passes between the plurality of input optical fibers 102, the first and second arrays of tilting mirrors 106, 108, and the plurality of output optical fibers 108 in so-called free space, i.e. without passing through any physical medium other than gas. Thus, once the beam of light 112 reflects from a tilting mirror in the second array 108, the light cannot scatter much while the beam travels to the output fiber before an insufficient amount of light is input into the output optical fiber. The beam of light 112 must hit the input end of the output fiber very nearly directly in order to transmit a sufficient amount of light through the output optical fiber.
Another factor that increases the difficulty of maintaining alignment of the tilting mirrors is vibration. The first and second arrays of tilting mirrors 106, 108 cannot withstand much vibration and maintain their precise alignment. The alignment of one or more tilting mirrors in the first and second arrays 106, 108 can be lost when the vibration sustained by the optical switch 100 becomes too great.